Class 12: First Test

Problem of the day

Pick a three digit number whose first digit is at least two larger than its third digit and call it M. Let R be the number obtained by reversing the digits. Then let N=M-R and again reverse the digits of N to get the number S. Compute the sum N+S. You get 1089. Explain why. Here's an example: Let M=523, so R=325, and N=523-325=198. Then S=891, and N+S=198+891=1089.

Assignment

Section 2.1, problems 6n+1, n=0,...,8; and 72

Brief review of the lecture

We discussed the test just taken and began the study systematic study of functions. There are three ways think about functions: A. as a table (data); B. as a formula (symbolic); and C. as a graph(pictorial). It is important to be able to convert from one form to another. Much of this matrial is not in the text. In the next few lectures, we'll talk about using functions to represent fragments of computer programs. This will help to understand composition of functions.

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